Triggers

Triggers are the components that initiate job execution. They define the conditions upon which they will
be fired. Many jobs are executed at a certain time each day or on maybe once per week. In the scheduler,
users can use the built in Calendar Trigger and configure it for their jobs to ensure jobs will execute at the desired times.

It may be required that a job be kicked off by some means other than a calendar trigger.
Perhaps a job needs to be activated when an email is sent to a specific inbox, or maybe there's a job that will delete
the last 6 months of log files when available disk space falls below a given threshold. These are all scenarios
that would advocate the use of a trigger as they require custom logic to determine when to kick off a job.

Jobs can also be configured to get kicked off from multiple triggers, allowing for a more flexible system that can
compose a set of discrete reusable conditions that kick off a job rather than forcing the creation of a single
trigger that contains the activation logic for a single unique job. The scheduler has a set of built-in
triggers, including a Calendar Trigger and the File Watcher Trigger, which will fire when specified changes to files
or folders occur. Users may create their own triggers by using the scheduler API.